Furthermore, consistent with the cyst wall not being synthesized in CS-induced differentiating cells (Fig. 1E), the transcription levels of the genes encoding the enzymes involved in chitin metabolism, e.g., chitinases 1 to 4 (Cht1 to 4) and chitin synthase (ChS1, 2), were not upregulated. This evidence concerns the gene SLC5A7 and cyst.